Many medical applications of collagen have already been described, whether in the form of pastes, for example for filling, of fluid or solid formulations, such as films or compresses, or in the form of diverse implants. In fact, only animal collagen is generally used.
The preparation of human collagen, which would be preferable to animal collagen, can be envisioned from human cutaneous tissues. However, it is made very difficult since the taking of human tissue samples from cadavers poses considerable ethical problems and requires expensive tests in order to eliminate the risks of transmission of infectious diseases, viral diseases or the like. The preparation of human collagen from placentas is expensive, complex and difficult to organize. The preparation of human collagen by the modern methods of genetic recombination or of cell culture is also very expensive, which would certainly impair the commercial development of this product.
Globin is the protein constituting hemoglobin, which, itself, contains 4 peptide chains (2 α-chains and 2 β-chains), each associated with a heme. The heme consists of a tetrapyrole structure containing one positively charged iron atom. There are 4 hemes per molecule, responsible for the red coloration of hemoglobin.
The processes for preparing globin have been known for a very long time and have been developed with dietary application being the aim, or for preparing injectable pharmaceutical solutions.
Unlike hemoglobin, which is completely soluble at physiological pH, globin is notably insoluble under the same conditions. The insoluble nature of globin under physiological conditions has, to date, impaired the development of its pharmaceutical applications. For this reason, most experiments have sought to prepare globin derivatives which are soluble at physiological pH, in particular by succinylation using succinic anhydride or by acetylation using acetic anhydride, or by hydrolysis of the amide functions at alkaline pH, which increases the negative charge of globin and decreases its isoelectric pH. An injectable product combining a soluble preparation of acid globin with insulin has been developed, patented and marketed: Reiner (1939); Reiner et al. (1939). It allows, after injection, gradual delivery of the insulin from this complex: Rabinowitch et al. (1947); Berg et al. (1953). Globin is not the active element or the main element of this product.